According to OSHA's Hazard Communication Standard, 29 CFR 1910.1200, employees have the right to obtain copies of any MSDS used in their workplace. High school chemistry students should be familiar with Material Safety Data Sheets and understand how to read them.

MSDSs are to be kept in a systematic and consistent manner, but the system is largely up to the employer. MSDSs can be kept in notebooks, file cabinets, or on data base, as long as employees are trained in how to manipulate the system and have ready access to the files. The Federal Hazard Communication Standard (FHCS) called for all chemical manufacturers to create new Material Safety Data Sheets by November 25, 1985. All MSDSs are not exactly alike, but they all must: have a date - If the data sheet is dated before Nov. 25, 1985, then chances are there is a more current version. list medical conditions that could arise or become aggravated by exposure to the chemical state whether the chemical is a carcinogen or contains any carcinogens state the primary routes of entry into the body list basic first-aid measures to administer for exposure to the substance

Section 1: Identity - The name of the substance. Some MSDS will have a common name, commercial name, chemical name, and formula.

Section 2: Hazardous Ingredients - If the substance has several components, all should be listed. Each hazardous substance and the exposure limits are listed.

Section 3: Physical/Chemical Characteristics - This section will tell you what to expect from the chemical. This is particularly important to guarantee proper handling, fire and spill address procedures.

BOILING POINT - The temperature at which the material boils. If the material is a mixture, a range might be given.

VAPOR PRESSURE - Tells how much vapor the material may produce. A high vapor pressure indicates that the material will readily evaporate.

VAPOR DENSITY - Tells how heavy a vapor is relative to an equal amount of air. A high vapor density means that the vapor will tend to accumulate at the bottom of tanks.

SOLUBILITY IN WATER - Indicates the solubility of the substance in water. Solubility is generally indicated numerically in weight percent. Solubility might also be expressed as follows:

Water Solubility Table:
• Negligible......................less than 0.1 percent solubility
• Slight..............................0.1 to1 percent solubilit
• Moderate......................1 to 10 percent solubility
• Appreciable....................more than 10 percent solubility
• Complete.......................soluable in all proportions

SPECIFIC GRAVITY - Indicates how heavy the material is relative to water.

Specific Gravity Table
• 1.0.................................same as water
• above 1.0....................heavier than water
• below 1.0.....................lighter than water

EVAPORATION RATE - You must exercise caution when interpreting evaporation rate data. There are two commonly used bases from which to derive a figure. Ethyl ether is used as the basis for determining evaporation rates of highly volatile solvents. In this case, values higher than 1 indicate less rapid evaporation than ether. Butyl acetate is the standard used for less volatile solvents and values greater than 1 indicate evaporation rates greater than butyl acetate.

MELTING POINT - Temperature at which a solid material melts.

APPEARANCE AND COLOR - The physical state of the substance at room temperature and any other physical characteristics that are obvious when looking at the substance..

Section 4: Fire and Explosion Hazard Data - This information is intended to help you in case of an emergency. Special attention should be taken to understand how to interpret the data in this section quickly and correctly

FLASH POINT - This figure indicates the temperature at which a material will ignite. There are two general methods used to determine flash point (closed cup and open cup), so the method used in the determination should be specified.

FLAMMABLE LIMITS - This gives the range of concentrations of a gas or vapor (percent by volume of air) which will burn or explode if exposed to an ignition source. Upper explosive limit (UEL) and lower explosive limits (LEL) are given.

EXTINGUISHING MEDIA - Cites the appropriate fire extinguishing media for the material.

SPECIAL FIRE FIGHTING PROCEDURES - A list of special provisions including personal protective equipment and procedures.

UNUSUAL FIRE AND EXPLOSION HAZARDS - Lists any peculiarities the material may demonstrate during fire fighting procedures. For example, this section could contain the following: "extremely flammable, water reactive, vapors heavier than air and could flow along floor to alternate ignition sources."

Section 5: Reactivity Data -This information helps the user determine safe storage procedures. This section should provide information on material stability and reactivity and should state what other chemicals or substances to avoid when handling the material.

STABILITY - Tells how easily a material becomes self-reactive and under what conditions it is most likely to do so.

INCOMPATABILITY - Tells what chemicals that the material might come in contact with that should be avoided.

HAZARDOUS DECOMPOSITION OR BYPRODUCTS - Lists hazardous chemicals that are produced if the material is burned, oxidized or heated.

HAZARDOUS POLYMERIZATION - Usually a yes or no response indicative of whether or not hazardous polymerization is likely to occur. If "yes" then conditions by which the reaction could take place should be listed.

Section 6: Health Hazard Data - This section gives pertinent health data and effects of exposure.

ROUTES OF ENTRY - This information tells you how the chemical is most likely to enter the body. Also indicated should be any potential routes of entry in a foreseeable emergency situation. A foreseeable emergency is one that might be expected as a consequence of something going wrong during the normal course of an employee's job, e.g. a tank explosion, burst pipe, accidental inhalation, ingestion, etc.

HEALTH HAZARDS - Indicates what the potential health effects of exposure to the material are and whether the effects are acute or chronic. Acute effects are those that occur from a concentrated dose of the material over a relatively short period of time. Chronic conditions are usually associated with continuous, low-level exposures, and do not appear for days, months, or even years after the initial exposure.

CARCINOGENICITY - Tells if the material is carcinogenic or not. A material is considered carcinogenic if it is specified as such by the National Toxicology Program's, Annual Report on Carcinogens, the International Agency for Research on Cancer, or OSHA.

SIGNS AND SYMPTOMS OF EXPOSURE - The most common symptoms of exposure are described in this section. Specific allergic reactions are rarely listed so there may be other danger signs not mentioned by the MSDS.

MEDICAL CONDITIONS GENERALLY AGGRAVATED BY EXPOSURE - Those medical conditions generally recognized as aggravated or complicated by exposure to the material.

EMERGENCY FIRST AID PROCEDURES - Self explanatory for the most part. It should be noted that these are first aid procedures only and a qualified medical person should be contacted and apprised of the situation as soon as possible.

Section 7: Control Measures - This section lists protective equipment to be used, types of ventilation and general precautions to consider.

RESPIRATORY PROTECTION - Type of respirator to use.

VENTILATION - Type of ventilation suggested for work with the material.

PROTECTIVE GLOVES - Gives construction (type of material) of the glove recommended for work with the substance.

EYE PROTECTION - Indicates type of eye protection.

OTHER PROTECTIVE CLOTHING AND/OR EQUIPMENT - Tells when special suits or protective equipment of any kind should be used.

WORK / HYGIENIC / MAINTENANCE PRACTICES - Indicates personal hygienic practices for working with the material, like washing hands, etc.

Glossary of Common MSDS Terms:

• Acute - Short term period of action. Readily apparent.
• Asphyxiant - A gas or vapor that can cause injury by reducing the amount of oxygen available for breathing.
• Carcinogen - A substance which has been identified as causing cancer in humans.
• Chronic - A long time period of action.
• Combustible Liquid - A liquid having a flash point at or above 1000F but below 2000F. This definition does not include mixtures containing one or more constituents with flash points outside the parameters indicated.
• Compressed Gas:
  1. a gas or mixture of gases having in a container an absolute pressure exceeding 40 pounds per square inch at 700F,
  2. a gas or mixture of gases having in a container an absolute pressure exceeding 104 pounds per square inch at 1300F, regardless of the pressure at 700F,
  3. a flammable liquid having a vapor pressure exceeding 40 pounds per square inch absolute pressure at 1000F, as determined by the American National Standard Method of Test for Vapor Pressure of Petroleum Products.
• Corrosive Material - A chemical capable of causing visable and irreversible damage to human skin tissue at the site of contact.
• Explosive - A chemical that produces a sudden release of pressure, gas and/or heat when subjected to sudden shock, pressure or high temperature.
• Exposure - Contact of an individual with a hazardous material during the course of employment through any route of entry.
• Flammable Material - A substance that meets any of the following specifications: A flammable aerosol is a chemical substance or mixture, dispensed from a container as a mist, spray or foam by a propellant under pressure, which yields a flame of at least 18 inches at full valve opening, or a flashback (flame extending back through the valve) at any opening. A flammable gas is a gas which, at normal atmospheric pressure and temperature and at a concentration of 13 percent or less, forms a flammable mixture, or that forms a range of flammable mixtures with air greater than 12 percent regardless of the lower limit. A flammable liquid for our purposes, is defined as having a flash point below 1000F except that this does not include any mixture where any one constituent has a flash point at or above 1000F and makes up 99 percent or more of the total volume of the mixture. A flammable solid is a material (other than an explosive) that causes fire through friction, absorption of moisture, spontaneous chemical change, retained heat from manufacturing or processing, or that can be readily ignited and can remain so even after the ignition source is removed.
• Flash Point - The minimum temperature at which a substance produces enough vapor to be ignited.
• Forseeable Emergency - Any potential occurrence that could result in the uncontrolled release of a hazardous material into the workplace. Hazardous Chemical Substance or Mixture - Is a substance considered as one or more of the following : a toxic material, a carcinogen, a corrosive material, an irritant, a strong sensitizer, a dangerously reactive material, a flammable material, a combustible liquid, a pyrophoric material, a strong oxidizer, an explosive material, or a compressed gas.
• Health Hazard - A relative term generally referring to any substance that has been shown by at least one established scientific study to produce acute or chronic detrimental health effects to exposed personnel.
• Irritant - A chemical substance or mixture, other than a corrosive, that when contacted with the skin produces an inflammatory reaction to the affected area and/or surrounding areas.
• Median Lethal Concentration LC50 - The concentration in air of gas, vapor, mist, fume or dust for a given period of time that will kill 50 percent of the test animals using a specified test procedure. Inhalation is the primary route of entry.
• Median Lethal Dose LD50 - The dosage of a substance that will kill 50 percent of the test animals to which the substance is administered using a specified test procedure. Various routes of entry can be used for testing purposes
• LEL (Lower Exposure Limit) - The lowest concentration of a gas or vapor in air that will ignite or explode if an ignition source is provided.
• Material Safety Data Sheet (MSDS) - An information document that contains relevant information about a specific chemical or mixture. Also lists the hazards of the chemical, appropriate emergency response procedures, protective equipment that should be worn, etc..
• Mutagen - A material that affects organisms at the genetic level and whose effects may be seen in subsequent generations.
• Oxidizer - A chemical that promotes combustion in other materials. The definition does not include explosives.
• Physical Hazard - A chemical that is either a combustible liquid, a compressed gas, an explosive, is flammable, an organic peroxide, an oxidizer, is pyrophoric, is reactive or water-reactive.
• Pyrophoric Material - A chemical substance or mixture that will ignite spontaneously in dry or moist air at a temperature below 130 ^oF.
• Reactive Material - A chemical substance or mixture that may vigorously polymerize, decompose, condense, or become self-reactive under conditions of shock, pressure or temperature. Includes chemical substances that can be classified as explosive, an organic peroxide, a pressure generating material or a water reactive material.
• Sensitizer - A chemical substance or mixture known to cause some form of hyper-sensitive reaction to normal tissue when said tissue is exposed to it.
• Teratogen - A chemical that causes physical defects in a developing embryo.
• Threshold Limit Values (TLV) - These are the upper exposure limits of airborne concentrations of chemicals that are accepted as safe for employees to be exposed to on a day-in, day-out basis. There are three types of threshold limit values.
  1. The Time Weighted Average (TWA) is the maximum concentration that employees working eight hours per day, 40 hours per week can be exposed to with no adverse physical effects.
  2. The Short Term Exposure Limit (STEL) is the maximum concentration to which workers can be exposed for a period of up to 15 minutes with no detrimental effects.
  3. The Ceiling (C) is the concentration that should never be exceeded, not even instantaneously.
• Toxic - Refers to any chemical or substance that falls into any of the following categories:
  1. A chemical that has a median lethal dose of more than 50 milligrams per kilogram but not more than 1000 milligrams per >kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each;
  2. a chemical that has a median lethal dose of more than 200 milligrams per kilogram but not more than 1000 miligrams per kilogram of body weight when administered by continuous contact for 24 hours or less with the bare skin of albino rabbits weighing between 2 and 3 kilograms each;
  3. a chemical that has a median lethal concentration in air of more than 200 ppm but not more than 2000 ppm by volume of gas vapor, or more than two milligrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for one hour or less to albino rats weighing between 200 and 300 grams each.
• Unstable - A chemical or substance in a pure state (nothing added) that will readily polymerize, decompose, condense, or become self-reactive under conditions of shock, pressure or temperature.